Method and apparatus for calendering plastic material



April 23, I935. F. D. FOWLER ,8

METHOD AND APPARATUS FUR CALENDERING PLASTIC MATERIAL Filed Nov. 15, 1933 2 SheetsSheet 1 38 3 5 [5 JP5- 4/ z 7 1 4 /0 v f o on g: 73

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METHOD AND APPARATUS FOR CALENDERING PLASTIC MATERIAL Filed Nov. 15, 1933 2 Sheets-Sheet 2 -v I Fri: 5 r gzi dj Ffi/i Patented Apr. 23, 1935 UNITED STATES METHOD AND APPARATUS FOR GALENDER- mo PLASTIC MATERIAL Fred D. Fowler, Newton, Mass., assignor to Hood Rubber Company, Inc., Watertown, Mass., a corporation of Delaware Application November 15, 1933, Serial No. 698,117

4 Claims.

This invention relates to methods and apparatus for calenderin'g plastic material to produce a sheet or slab in which one longitudinal zone is thicker than another portion. The invention is especially useful in the production of sheet material for making shoe soles, tire treads, or other articles requiring a slab having longitudinal zones of different thicknesses;

Where it is desired to calender a mass of plastic material such as rubber to provide a strip having different thicknesses in different longitudinal zones, this may be done by providing the calender with a final pass defined by rolls one or more of which is circumferentially grooved or contoured to provide the desired shape. As the plastic material is usually supplied to the rolls in a sheet or slab of uniform thickness and the thicker part of the strip requires a, greater supply of material in a given time than the thin part of the strip, difiiculty is experienced in securing satisfactory results without overfeeding some portions of the bight of the rolls and thereby causing excess working and possibly prevulcanization of the material.

The principal objects of this invention are to provide a novel method of overcoming the aforesaid difficulties and toprovide suitable apparatus therefor.

Other objects will appear from the following description and the accompanying drawings.

Of the drawings:

Fig. 1 is a plan View of apreferred form of apparatus embodying the invention.

Fig. 2 is a front elevation thereof, the lower part of the frame being broken away. a

Fig. 3 is a sectional view taken on line 3-3 of Fig. 1.

Fig. 4 is a perspective View of part of a finished slab of rubber.

Referring to the drawings, the numerals I 0, I0 designate the side frame members of a calender adapted to form a plastic rubber mass, into sheet or slab form. The frame members are provided with journal boxes in which are rotatably mounted in parallelism a series of calender rolls I2, I3, I4 and I5. Rolls I2, I3 and I4 are of the usual construction with plain faces. Means (not shown) are provided for circulating water and steam through the rolls, which are hollow, for regulating the temperature thereof.

Roll I3 is mounted to rotate in bearings fixed to the frame members, whereas the rolls I2 and I4 are mounted in bearing boxes adjustable toward and from roll I3 to regulate the space between the rolls.

Roll I5 is similarly adjustable toward and from roll I4, screws I6 being provided for making the adjustment. Roll I5 is contoured or formed with a circumferential groove for forming the thick zone of the slab.

The plastic material H, which has been previously warmed, is entered between rolls I2 and I3 where it assumes the form of a sheet I8. This sheet passes around roll I3 and between rolls I3 and I4 where it is further rolled to size.

As the sheet I8 passes roll I4,'a spring pressed knife I9 mounted upon the frame of the machine rests against roll I4 and divides or slits the sheet into a narrow strip and a wide strip 2|: Strip 2| proceeds around an idler roll 22 and between rolls I4 and I5.

The strip 20 is conveyed to the bight of rolls I4 and I5 Where it is superimposed upon stripZI at the grooved portion of roll I5. For this purpose a drum 23 mounted on a shaft 24 is rotatably mounted on brackets 25, 25 extending from the frame members above the calender. Drum 23 is driven by a belt 26 from a pulley 21. Pulley 21 is mounted on a shaft 28, journaled in a bracket 29 on the machine frame. It is driven from roller 22 by a belt 30 which drives a pulley 3|, pulleys 21 and 3I being connected by a universal joint 32. The drive may be omitted if desired and the drum 23 driven by the stock. The

arrangement is such that the strips are laterally rearranged in proportion to the usage of rubber along the face of the rolls.

Idler rolls 33 and 34 are provided to guide the strip 20.

The strips 20 and 2| supply the necessary amount of rubber properly distributed to supply the bight of rolls I4, I5, where the slab illustrated in Fig. 4 is formed. Roll I5 may be knurled or otherwise engraved to produce a pattern on the face of the slab.

I claim: v

1. Apparatus for forming a slab of plastic material of non-uniform cross-section,'said apparatus comprising a pair of forming rolls adapted to roll the desired section, and feeding means for supplying plastic material thereto in strip form, said feeding means comprising a sheet forming roll directly cooperating with one of the forming rolls, a cutter cooperating therewith to slit the sheet into strips, and delivery means to supply one strip ofmaterial of narrow width in superimposed relation to another strip of greater width thereby to supply more material at a position requiring greater supply.

2. Apparatus for forming a slab of plastic material of non-uniform cross section, said apparatus comprising a pair of forming rolls adapted to roll the desired section, and means for feeding a supply of plastic material thereto, said means including a pair of calender rolls directly cooperating with one of the forming rolls for forming a sheet of material, cutting means cooperating therewith to slit the sheet into strips, and means for so delivering the strips to the forming rolls as to supply material at difierent positions along the bight of the rolls in proportion to the volume consumed at each position. I

3. Apparatus for forming a slab of plastic material of non-uniform cross-section, said apparatus comprising a pair of forming rolls adapted to roll the desired section, and. means 101' feeding a supply of plastic material thereto, said means including a pair of calender rolls for forming a sheet of material of uniform thickness, a. cutter cooperating with one of the rolls to slit said sheet to form a wide strip and a narrow strip, means for leading the wide strip to the bight of the forming rolls, and means for conveying the narrow strip to the bight of the forming rolls in superimposed relation to the wide strip. 7

4. The method of forming a slab of plastic material of non-uniform cross section which comprises calendering a sheet of plastic material, slitting the sheet to provide a narrow strip and a wide'strip, advancing the strips while arranging them in juxtaposed relation, and rolling the assembled strips to form the desired slab.

FRED D. FOWLER. 

